export from one field of packets

edit

tshark is good for exporting fields:

~$ tshark -r ./output.pcap -T fields -e frame.number -e tcp.flags.str -Y tcp.flags.str
50      ·······A···F
51      ·······AP···
52      ·······AP···
53      ·······A····
...

Adding the -Y option with the field name prevents printing blank lines for frames that don't include the field.